The invention pertains to feed and mixer apparatus, usually of the portable type which is pulled by a tractor and which receives power therefrom, the apparatus having a hammermill and a supplemental feed hopper through which crop material is fed and then mixed together for delivery to a mixing tank. The hammermill acts to grind the crop material, such as grain, hay and so forth and removes the dust laden air therefrom and delivers it to a dust collector. The ground crop material is received by a feed screw auger which conveys it rearwardly to the mixing auger. Supplemental feed is also introduced into the feed screw auger for delivery along with the ground material to the mixing tank where the two materials are then thoroughly mixed. Devices of this type are shown in the U.S. Pat. No. 3,199,796 issued Aug. 10, 1965 and entitled "Portable Feed Grinder and Mixer"; U.S. Pat. No. 3,735,932 issued May 29, 1973 and entitled "System for Overcoming Transport-Particle-Flow Deficiencies Inherent in Feed Grinding and Mixing Machines using Dust Collectors for the Grinder"; and U.S. Pat. No. 3,840,189 issued Oct. 8, 1974 entitled "Feed Mill and Mixer".